With the vigorous development of INTERNET, Broadcast TV (BTV) service based on IP network emerges. BTV transfers video programs via IP network, so that a family may have the same service experience as the current TV. At the same time, by using the characteristics of IP network, more abundant functions, such as for supporting video phone, video conference, distance education and the like, may be provided on a home TV terminal.
FIG. 1 shows a network model of BTV service in the prior art. Referring to FIG. 1, BTV service is transferred in an IP network from a head-end to a home in multicast mode. Inside the home, video stream is transferred to TV terminals with a set-top box (STB) via a home gateway.
FIG. 2 shows a network model for realizing BTV service in the prior art. Referring to FIG. 2, in order to realize fast channel switching, in a technical solution of the prior art, a program authorization table of programs that may be watched by a user is installed in advance to a digital subscriber line access multiplexer (DSLAM) closest to the user (in step 1a of FIG. 2, a program authorization table is configured statically via the configuration policy of an operation support system (OSS) or a policy server;
Alternatively, in step 1a′ of FIG. 2, a user registers on an IPTV service management system, and in step 1b′, the IPTV service management system issues the user policy to the edge device and dynamically issues a program authorization table). After obtaining the program authorization table, the DSLAM queries the program authorization table to determine whether to allow a user to watch the corresponding program according to a request sent by the user for joining a channel. If the user passes the verification, a multicast media stream requested will be replicated to the corresponding user port. In addition, if quality of service (QoS) needs to be guaranteed, the DSLAM will request a resource server to reserve a corresponding bandwidth resource for the multicast media stream (in FIG. 2, resource reservation request in step 3, and resource reservation response in step 4). If the corresponding multicast stream does not reach the DSLAM in advance, the DSLAM device will upload the IGMP request message to a BNG device to establish a transfer channel. Or, the resource server establishes a multicast channel with QOS guaranteed to the DSLAM.
The above technical solution can realize fast channel switching. But because the program access authorization table of a user is issued to the DSLAM in one go, there lacks detail and flexible program control on the user. For example, IPTV service operator may wish to control the number and content of programs that may be watched by a family at the same time, or to control different authorizations granted to different users of the same family, then the control force of such a simple control table is rather limited.
FIG. 3 shows another network model for realizing BTV service in the prior art. Referring to FIG. 3, FIG. 3 shows the second method for realizing BTV service in the prior art, which includes the following steps:
1. A User Equipment (UE) sends a service request to an IPTV server for establishing a session;
2. After the IPTV server authorizes the service request of the user, it sends a request to a policy/resource control server;
3. The policy/resource control server performs admission control on the network resource and controls a bearer network to establish a multicast channel with QOS guaranteed;
4. The media stream is issued to the UE via the multicast channel established;
4′. The policy/resource control server responds to the request of the IPTV server;
5. The IPTV server responds to the user via a business layer session.
In this solution, the user service authorization policy is put on a centralized server and every channel request needs to be handled by the server. This mode of ‘centralized control’ will cause much delay in reality and thus it is difficult to realize fast channel switching.